Online you can find many guides to follow when building your disaster recovery plan. The guides will outline your plan and what you need to do. Furthermore, they will give you test points to check, tell you when to test your plan, and how to modify your plan. I would download a few white papers to follow. They are a good place to start.
There are some excellent online tutorials that can help you get started. Here they will walk you though building your plan step-by-step. You might want to hire a company to do this for you. That is what we did. It is well worth the investment.